1. Field of the Invention
The present invention relates to a peripheral circuit of a touch panel and a manufacturing method thereof.
2. Description of the Prior Art
Various types of touch technology are widely applied in electronic products. For example, in mobile phones and tablets, touch panels are often utilized as an input interface. The user can use their hand to directly contact the surface of the touch panel for performing operations, or slide their hand on the surface of the touch panel to control a mouse or perform a hand-written input. A display together with the touch panel may also show a virtual keyboard for the user, and the user can input characters via corresponding keys on the virtual keyboard.
The touch panel may be divided into various types such as a resistive touch panel, capacitive touch panel, ultrasonic touch panel and infrared ray touch panel. Among these touch panels, the resistive touch panel is the most commonly utilized. The resistive touch panel may mainly be divided into a four-wire touch panel, five-wire touch panel, six-wire touch panel and eight-wire touch panel. Since the four-wire touch panel is more mature in consideration of cost and technology, it is currently the most widely manufactured. The capacitive touch panel, however, can sense a light-touch, and thus is more convenient for utilization. In addition, the capacitive touch panel rarely wears down due to finger contact. It is also more stable and has a longer life than the resistive touch panel. For these reasons, the capacitive touch panel is gradually replacing the resistive touch panel as the most commonly utilized touch panel applied in electronic products.
The touch panel includes a substrate, a transparent conductive layer formed on the substrate, a peripheral circuit and an insulating layer. The touch panel may further include a connected flexible printed circuit board (FPC). The peripheral circuit is connected with the transparent conductive layer and the FPC. The peripheral circuit can be formed by a photolithography process. The conventional photolithography process includes the following steps: first, a metal layer is formed on the substrate by deposition or electrode planting; then a photoresist layer is applied on the metal layer, and selective exposure is performed on the photoresist layer; then developing is performed on the photoresist layer after exposure with a developer, to obtain a patterned photoresist layer; finally, the patterned photoresist layer is utilized as a mask to etch the metal layer, in order to form a conductive circuit on the substrate.
When the conventional photolithography process is implemented, the steps are complex and need to utilize a large number of chemicals, such that the cost is high and the process may not comply with the requirements and trends of environmental protection emphasized in modern science and technology.
In order to solve the problems of manufacturing the peripheral circuit with the conventional photolithography process, the industry provides a manufacturing method for forming the peripheral circuit with a printing process. This method prints a thermal setting conductive adhesive on the substrate, and then cures and bakes the thermal setting conductive adhesive with a high temperature, in order to form the peripheral circuit. This manufacturing method benefits from a simplified process in comparison to the photolithography process, but the peripheral circuit formed by utilizing the printing process may come off since the adherence degree of the printing ink connected with the substrate is low, which causes the conductive circuit to be cut off. In addition, this method may only be applied in a conductive pattern and circuit with a thicker wire width and a greater wire distance, and cannot effectively enhance the density of circuit disposition.
Therefore, how to provide a peripheral circuit of a touch panel and a manufacturing method thereof which are capable of reducing wire width or wire distance in order to achieve higher integration while complying with environmental protection requirements becomes an important issue.